title: Nonfunctional pancreatic neuroendocrine tumors <2 cm on preoperative imaging are associated with a low incidence of nodal metastasis and an excellent overall survival.
abstract: BACKGROUND
  The optimal surgical management of small nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) remains controversial. We sought to identify (1) clinicopathologic factors associated with survival in NF-PNETs and (2) preoperative tumor characteristics that can be used to determine which lesions require resection and lymph node (LN) harvest.
  
  
  METHODS
  The records of all 116 patients who underwent resection for NF-PNETs between 1989 and 2012 were reviewed retrospectively. Preoperative factors, operative data, pathology, surgical morbidity, and survival were analyzed.
  
  
  RESULTS
  The overall 5- and 10-year survival rates were 83.9 and 72.8 %, respectively. Negative LNs (p = 0.005), G1 or G2 histology (p = 0.033), and age <60 years (p = 0.002) correlated with better survival on multivariate analysis. The 10-year survival rate was 86.6 % for LN-negative patients (n = 73) and 34.1 % for LN-positive patients (n = 32). Tumor size ≥2 cm on preoperative imaging predicted nodal positivity with a sensitivity of 93.8 %. Positive LNs were found in 38.5 % of tumors ≥2 cm compared to only 7.4 % of tumors <2 cm.
  
  
  CONCLUSIONS
  LN status, a marker of systemic disease, was a highly significant predictor of survival in this series. Tumor size on preoperative imaging was predictive of nodal disease. Thus, it is reasonable to consider parenchyma-sparing resection or even close observation for NF-PNETs <2 cm.
authors.affiliation: Division of General Surgery, Department of Surgery, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, CA, USA, ptoste@mednet.ucla.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Toste
authors.forename: Brian E
authors.initials: BE
authors.lastname: Kadera
authors.forename: Sergei F
authors.initials: SF
authors.lastname: Tatishchev
authors.forename: David W
authors.initials: DW
authors.lastname: Dawson
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Clerkin
authors.forename: Raman
authors.initials: R
authors.lastname: Muthusamy
authors.forename: Rabindra
authors.initials: R
authors.lastname: Watson
authors.forename: James S
authors.initials: JS
authors.lastname: Tomlinson
authors.forename: Oscar J
authors.initials: OJ
authors.lastname: Hines
authors.forename: Howard A
authors.initials: HA
authors.lastname: Reber
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Donahue
mesh_terms: D000368:Aged; D000818:Animals; D013505:Digestive System Surgical Procedures; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000175:diagnosis / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D010190:Pancreatic Neoplasms / Q000175:diagnosis / Q000401:mortality* / Q000473:pathology* / Q000601:surgery